1. Field of the Invention
This invention relates to a method of stripping an insulated magnet wire, and an apparatus for practicing the method. The method and apparatus are to be used when it is required to process the end portion of an insulated magnet wire which has been wound, for instance, with a motor winding machine.
2. Related Art
The term "magnet wire" as used herein is intended to mean an electrical wire which is fabricated by forming an insulating layer of polyamide, poly-urethane or enamel on a conductor.
In an electric motor, a magnet wire is wound on the protruded poles of the armature of the electric motor by using a winding machine as required, and the end portions of the magnet wire are electrically connected to, for instance, soldering terminals on a circuit board on which a motor driving circuit has been formed.
In order to solder the end portions of the magnet wire to the soldering terminals, it is necessary to strip the end portions of the magnet wire; i.e., to remove the insulating layer from it.
For this purpose, heretofore a magnet wire stripping apparatus as shown in FIGS. 18 through 20 is used.
As shown in FIGS. 18 through 20, in the conventional apparatus, the magnet wire 20 is passed through a tubular wire guide 54, and three arms 51 each having a blade 52 are arranged at angular intervals of 120.degree. around the wire guide 54.
Each of the arms 53 is mounted on a shaft 56 in such a manner that it is rotatable in a plane including the central axis of the wire guide 54, and is so urged that the edge of the blade 52 is brought into contact with the magnet wire 20.
The wire guide 54 is movable longitudinally with respect to the arms 51, so that the arms 52 are swingable from the positions where the edges of the blades 51 are in contact with the magnet wire 20 to the positions where they leave the magnet wire 20.
As shown in FIG. 20, the arms 51 are able to turn around the magnet wire 20 together with the wire guide 54 with the edges of the blades 52 kept in contact with the magnet wire.
With the apparatus, the magnet wire is stripped as follows: With the magnet wire 20 protruded from the wire guide in the direction of the arrow as shown in FIG. 19, the arms 51 are moved downwardly while being turned around the magnet wire in the above-described manner. In this operation, the edges of the blades 52 are brought into contact with the magnet wire 20 while drawing spiral lines on it. As a result, as shown enlarged in FIG. 21, the insulating layer is removed from the magnet wire 20 as indicated at 20c.
After the stripping operation, the wire guide 54 is moved upwardly in FIG. 19, and the arms 51 are turned against the arm urging forces until the edges of the blades 52 are moved away from the magnet wire.
In the above-described magnet wire stripping apparatus, a plurality of arms having blades are arranged radially around the magnet wire. That is, the arms occupy a relatively large space radially of the magnet wire. Hence, sometimes it is difficult to set the apparatus in the limited space in a given winding machine, or it is difficult for the apparatus to operate in the limited space.
On the other hand, the apparatus, being made up of the wire guide, the arms having the blades, and the shafts rotatably supporting those arms, is unavoidably intricate in construction.
In the case where, as shown in FIG. 22, a winding 22 is formed by winding a magnet wire 20 on a protruded pole 21 of the armature of a motor, and it is required to remove the insulating layer from the end portions of the magnet wire 20; in order to bring the edges of the blades 52 into contact with the magnet wire 20 by turning the arms 51 in planes including the central axis of the magnet wire 20 it is necessary to turn the arms 51 in such a manner that the edges of the blades 52 are not brought into contact with the winding 22. Hence, the portion L1 of the magnet wire which corresponds to the dimension of the blade 52 cannot be striped. In other words, it is impossible to strip the magnet wire from exactly beside the winding 22.